body {
    font-family: -apple-system, "Hiragino Kaku Gothic ProN", sans-serif;
    margin: 0;
    color: #222;
}
header {
    background: #1f2937;
    color: white;
    padding: 0.75rem 1.5rem;
}
header nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
header a {
    color: white;
    text-decoration: none;
}
header ul {
    list-style: none;
    display: flex;
    gap: 1rem;
    margin: 0;
    padding: 0;
}
main {
    padding: 1.5rem;
    max-width: 1100px;
    margin: 0 auto;
}
.flash {
    background: #fef3c7;
    padding: 0.5rem 1rem;
    margin: 0.5rem 1.5rem;
}
table {
    border-collapse: collapse;
    width: 100%;
}
th, td {
    border: 1px solid #e5e7eb;
    padding: 0.4rem 0.6rem;
    text-align: left;
}